SCAVENGERS OF REACTIVE OXYGEN SPECIES (ROS)
Good evening to all. Let me first congratulate all my Skills Tests-2010 competitors for crossing up all the hurdles and for reaching this level in the contest. I thank Pharmainfo.net for giving this opportunity and my mentor Mr. P.Manasa for his uplifting support. I am going to deal with the topic titled "Scavengers of Reactive Oxygen Species (ROS)" as my first half for march-2010.
Entering into the topic, by this time, we all may have a clear-cut idea regarding ROS definition, their generation which was explained elaboratively by my team-mate Ch.Pratibhanusha in her blog. Please visit: http://www.pharmainfo.net/pratibhanusha-chstanns/reactive-oxygen-species-ros-%E2%80%93-very-hungry-little-enemies-our-body-0
So, ROS are explained as the chemical species which are provided with a single unpaired electron in their outer shell configuration (1). These ROS are highly reactive and can aggressively attack all the other molecules surrounding within the cell (2).
EFFECTS OF ROS:
ROS can damage DNA, Proteins, Fatty acids, causes Cardio-vascular disorders, Brain-damage, kidney disease, arthritis, Aging, cataracts and the list goes on and on..........................(1)(2)(3)
SCAVENGERS OF ROS:
To defend our body against the damages caused by ROS, our body generally possesses some anti-oxidant defense mechanisms. These mechanisms include Anti-Oxidant molecules and some Enzymes (4). Antioxidants are the nutrients that cease the oxidation of various cells that is initiated by ROS (5). The main objective of these antioxidant molecules and enzymes is to donate an electron to ROS or to rob an electron from them in order to neutralize them Generally, in children and in youths, the antioxidant arsenal in body found to be sufficient for limiting this oxidation resulted by ROS. But when we reach our twenties, these defensive mechanisms gradually goes on declining; and at this stage, ROS have more chances to ruin/damage our body. So, for this reason, Researchers believe that an increased intake of anti-oxidants must be supplied through dietary improvements (4).
HOW ANTI-OXIDANTS WORK:
Figure 1: ref (6) Figure 2: ref (14)
SOURCES OF ANTI-OXIDANTS:
Antioxidants may be present Endogenously (i.e, present naturally within the body) or obtained Exogenously (i.e. from dietary sources). Let us first have a look on the Endogenous Sources.
A) ENDOGENOUS SOURCES: These include the ENZYMES like: (1)
? SOD (Super oxide dismutase)
? Super-oxide reductases (1)
The main objective of these enzymes is to neutralize the ROS whenever they are formed within the body (4). Of the above mentioned enzymes, SOD and Catalase are found to be major anti-oxidant defenses against ROS (1).
? SOD can exist in 2 forms - Cu/Zn SOD (in cytoplasm) & Mn-SOD (in mitochondria). Mn-SOD detoxifies Super oxide Anion into H2O2. (1)
? Thus formed H2O2 is then converted into water by the action of Catalase. (1)
? The enzyme Glutathione Peroxidase is necessary for converting the Glutathione into oxidized Glutathione and during this process, H2O2 is converted into water. (7)
B) EXOGENOUS SOURCES: (Dietary Sources)
As I have already mentioned that as we reach our twenties, there will be a decline in the effectiveness of our naturally provided antioxidant-systems i.e. the endogenous antioxidants. So, intake of antioxidant supplements in our diet is must to keep away the harmful effects of ROS. These act by interrupting the chain reaction initiated by ROS in body. The major dietary antioxidants include:
? Vitamin-E - This is a most abundant antioxidant and is fat-soluble. It acts as efficient chain breaker and thus defends against oxidation (8). It provides skin care and health (9).
? Vitamin-C - A water soluble vitamin that acts as powerful antioxidant. (10)
? Flavonoids - These are the water soluble, natural pigments present in plants and flowers (11). Rooibos are rich in flavonoids. Other sources include onions black-berries, green tea, cherries, lemons, oranges etc (12).
? Vitamin-B - less potent antioxidant (10)
? Carotenoids - found in fruits and vegetables. (4)
? Lipoic acid - It is considered antioxidant as it produces ATP by break downing of sugars. It elevates the action of other antioxidants such as vit-C, vit-E etc.
Some Strongest Antioxidant minerals include:
? Selenium etc.
Chocolate, Red wine, grape seed extract, russet potatoes, coffee, various vegetables, fruits, spices etc have been fount to be rich in antioxidants. (9) (13)
"The Role of Bioflavonoid as a ROS Scavenger" is discussed by my team mate Miss T.Sowjanya. Please visit
(1) (Accessed on March 16th, 2010)
(2) (Accessed on March 15th, 2010)
(3) (Accessed on March 20th, 2010)
(4) (Accessed on March 13th, 2010)
(5) (Accessed on March 11th, 2010)
(6) (Accessed on March 17th, 2010)
(7) (Accessed on March 17th, 2010)
(8) (Accessed on March 16th, 2010)
(9) (Accessed on March 14th, 2010)
(10) (Accessed on March 16th, 2010)
(11) (Accessed on March 21st, 2010)
(12) (Accessed on March 22nd, 2010)
(13) (Accessed on March 16th, 2010)
(14) (Accessed on March 16th, 2010)
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